1. Technical Field
The present invention relates to a radio-controlled timepiece and to a method of adjusting the time displayed by a radio-controlled timepiece.
2. Related Art
Radio-controlled timepieces that receive a radio signal containing time information (a longwave standard time signal) and automatically adjust and display the time based on the received time information are known from the literature.
A standard time signal is output, for example, at one second intervals, uses three different pulse widths to indicate the time, and takes one minute to send one complete time code.
Determining the time from these standard time signals typically requires continuously receiving the time signal for several minutes in order to receive the full time code plural times consecutively so that plural time codes can be compared to ensure the accuracy of the received time information. Adjusting the time therefore consumes much time and power.
Addressing this problem, Japanese Unexamined Patent Appl. Pub. 2005-315809 teaches a radio-controlled timepiece that detects the difference between the change in the signal level of the seconds pulse of the standard time signal and the seconds information of the internal timekeeping unit, and adjusts the seconds information of the internal timekeeping unit so that the average of plural difference values goes to zero, thereby enabling adjusting the time without receiving the full time code.